The present invention relates to conical crushers, and, more specifically, discloses structural features which enable a conical crusher to operate with a power draw twice that of unit designed according to conventional standards, as well as a method of determining crusher design parameters for achieving optimum performance. Crusher performance refers to the total throughput of comminuted material, as well as to the average particle size of that material.
Generally, a conical crusher is comprised of a head assembly including a conical crusher head which gyrates about a vertical axis by means of an eccentric mechanism. The eccentric is driven by any one of a number of power drives. The exterior of the conical head is covered by a wearing mantle which actually engages the material being crushed. Spaced from the head assembly and supported by the crusher frame is a bowl fitted with a liner comprising the opposing surface of the mantle for crushing the material, be it coal, ore, or minerals.
Conical crusher heads have basically two operating orientations. The first or "no-load" occurs when no material is being introduced into the crusher, but the crusher must be kept running due to its inability to initiate the rotation of a stopped head against the force exerted by a hopper full of rock. In the "no-load" orientation, the crusher head rotates in unison with the eccentric.
The second, or "on-load" orientation occurs when material is introduced into the crusher. The force of crushing the feed material on the conical head causes it to rotate in a direction opposite that of the eccentric. Most crushers have some type of anti-spin or head braking device which slows the "no-load" rotational velocity of the head, due to the unsafe tendency of crushers to violently fling the first particles of material introduced, causing injury to operators and/or damage to the crusher.
Conventional anti-spin devices are not suitable for large crushers due to space requirements and are a costly addition to those smaller crushers that can accommodate them.
Current market considerations in the mining and aggregate industries have forced crusher operators to be more cost effective than in the past. This drive for greater efficiency has created a demand for conical crushers which consume significantly less energy per ton of crushed material per crushing station. Also, existing physical crusher support facilities should be utilized whenever possible when implementing cost effective-technology.
There are several aspects of a conical crusher which must be adapted to achieve the goal of increased production on an existing foundation. These include a crusher frame and shell design which can withstand the increased stress forces generated by a twofold increase in power without increasing external frame dimensions. Another area of concern is the hydraulic circuit, which must be capable of rapidly passing tramp material and resuming operation after clearing to minimize downtime. To achieve this latter goal, a hydraulic circuit is needed which positively secures the crusher bowl during crushing and allows the bowl to raise from, and lower to a previous operating position during a clearing cycle.
It is therefore an object of the present invention to provide a crusher of significantly increased capacity and power rating which can be installed on an existing crusher foundation.
It is a further object to provide a simplified antispin device capable of adequately restraining the "no-load" rotation of a conical head of a crusher.
It is an another object of the present invention to provide an improved crusher frame shell design which possesses increased stress support while minimizing frame mass.
It is still another object of the present invention to provide a crusher hydraulic system having a counterbalance feature which holds the bowl elevated for clearing purposes, yet permits the hydraulic jack to completely retract once the bowl is returned to its normal operating position.